move yarn to its own directory
remove core/src/hadoop{1,2} dirs
dynamically detect hadoop version
yarn sbt
remove hadoop-yarn's org/apache/...
add comment
Fix setting of SPARK_EXAMPLES_JAR
yarn support
rename HadoopMapRedUtil => SparkHadoopMapRedUtil, HadoopMapReduceUtil => SparkHadoopMapReduceUtil
make SparkHadoopUtil a member of SparkEnv
SparkEnv isn't available this early, and not needed anyway
re-enable YARN support
YARN ApplicationMaster shouldn't wait forever
update YARN docs